cl-cookbook-contrib

[cl-cookbook-contrib] [ cl-cookbook-Bugs-546193 ] sockets example newline error

[<no...@so...>]

Bugs item #546193, was opened at 2002-04-19 11:30
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=447472&aid=546193&group_id=46815

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: John Wiseman (jjwiseman)
Assigned to: Nobody/Anonymous (nobody)
Summary: sockets example newline error

Initial Comment:
The sockets http example makes a common mistake by
using read-line for reading lines and ~% to output
newlines.

HTTP lines are terminated by CR LF.  ~% may output LF
on a unix system, CR on a Mac, and CR LF in Windows. 
Similarly, read-line will consider a line to be
terminated by diffrent characters or sequences of
characters on different systems.



----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=447472&aid=546193&group_id=46815

[cl-cookbook-contrib] [ cl-cookbook-Bugs-546193 ] sockets example newline error

[<no...@so...>]

Bugs item #546193, was opened at 2002-04-19 11:30
You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=447472&aid=546193&group_id=46815

Category: None
Group: None
>Status: Open
Resolution: Fixed
Priority: 5
Submitted By: John Wiseman (jjwiseman)
Assigned to: Alberto Riva (albertoriva)
Summary: sockets example newline error

Initial Comment:
The sockets http example makes a common mistake by
using read-line for reading lines and ~% to output
newlines.

HTTP lines are terminated by CR LF.  ~% may output LF
on a unix system, CR on a Mac, and CR LF in Windows. 
Similarly, read-line will consider a line to be
terminated by diffrent characters or sequences of
characters on different systems.



----------------------------------------------------------------------

>Comment By: John Wiseman (jjwiseman)
Date: 2002-06-07 01:31

Message:
Logged In: YES 
user_id=374464

The code still uses read-line to read HTTP requests, and
uses #\Newline when sending HTTP requests.

I think the most portable replacement for #\Return and
#\Newline (which is actually a carriage return on Mac OS
before 10, e.g.) is to use (code-char 13) and (code-char 10).

I've attached code I've used to read telnet-style
CRLF-terminated lines in several lisps, you might want to
use something like this.

(defun read-telnet-line (stream eof-error-p eof)
  "Read a CRLF-terminated line"
  (if (stream-eof-p stream)
    eof
    (let ((line (make-array 10 :element-type 'character
:adjustable t :fill-pointer 0))
          (char nil))
      (do () ((or (eq eof (setq char (read-char stream
eof-error-p eof)))
                  (and (eql char *cr*) (eql (peek-char nil
stream) *lf*)))
              (when (not (eq char eof)) (read-char stream))
              (values line (null char)))
        (vector-push-extend char line)))))


----------------------------------------------------------------------

You can respond by visiting: 
http://sourceforge.net/tracker/?func=detail&atid=447472&aid=546193&group_id=46815

Re: [cl-cookbook-contrib] [ cl-cookbook-Bugs-546193 ] sockets example newline error

[Lieven M. <ma...@wy...>]

no...@so... writes:

> Bugs item #546193, was opened at 2002-04-19 11:30
> You can respond by visiting: 
> http://sourceforge.net/tracker/?func=detail&atid=447472&aid=546193&group_id=46815
> 
> Category: None
> Group: None
> Status: Open
> Resolution: None
> Priority: 5
> Submitted By: John Wiseman (jjwiseman)
> Assigned to: Nobody/Anonymous (nobody)
> Summary: sockets example newline error
> 
> Initial Comment:
> The sockets http example makes a common mistake by
> using read-line for reading lines and ~% to output
> newlines.
> 
> HTTP lines are terminated by CR LF.  ~% may output LF
> on a unix system, CR on a Mac, and CR LF in Windows. 
> Similarly, read-line will consider a line to be
> terminated by diffrent characters or sequences of
> characters on different systems.

I usually work around this problem by using a MAKE-STREAM-CRLF-ENDED
function that is implemented by using MOP and Gray streams. This could
make an example for this kind of technique. In general, the cost of
network latency makes this efficient enough for clients

-- 
Lieven Marchand <ma...@wy...>
She says, "Honey, you're a Bastard of great proportion."
He says, "Darling, I plead guilty to that sin."
Cowboy Junkies -- A few simple words

Re: [cl-cookbook-contrib] [ cl-cookbook-Bugs-546193 ] sockets example newline error

[Alberto R. <Alb...@TC...>]

Lieven Marchand wrote:
> 
> I usually work around this problem by using a MAKE-STREAM-CRLF-ENDED
> function that is implemented by using MOP and Gray streams. This could
> make an example for this kind of technique. In general, the cost of
> network latency makes this efficient enough for clients

Lieven, you're welcome to add an example of your technique to the page, 
or send it to me. My example was oversimplified since the page was 
already long enough. In real life, I've found that browsers have no 
problems accepting LF-terminated lines. In the other direction, I just 
strip the extra CR from the line returned by READ-LINE.

I also have code  (mostly provided by Franz for ACL 6) to support 
different line terminators using their own simple-streams. Maybe we 
could put the two solutions together in a new page about haw to deal 
with different encodings.

Alberto


-- 
Alberto Riva
Children's Hospital
Informatics Program